I purchased the PS31 Garmin Panoptix forward vu. I am about to mount it on the transom and the instructions indicate to mount at a 45 degree angle. The unit is not rated for above 25mph. Does this mean it wont work at this angle, or do not drive the boat above this speed. (I travel at 45mph to get to the fishing grounds, then troll at 3-5mph (Chesapeake Bay). Should I return the unit as not worth using?